This invention relates to an improved biolytic filtration protocol for wastewater and solid organic waste material, and is particularly concerned with the use of a structural framework to facilitate such filtration protocol.
The type of biolytic filtration with which the present invention is concerned, is the subject of a portfolio of patents held by the applicant and which is typified by U.S. Pat. No. 5,633,163. The biolytic filtration consists of the simultaneous treatment of wastewater and solid organic waste material on a bed of solids in various stages of decomposition ranging from raw unprocessed organic material added to the surface of the bed, through to fully decomposed humus which is a very active filtration matrix and which forms the bulk of the bed. The bed is kept from blocking through the action of a farm of living organisms selected from worms, insects, crustaceans, mites and the like which create pores throughout the filtration matrix. The humus matrix column is in fact a ‘structured water column’ such that oxygen is still able to penetrate the column. The humus matrix is only approximately 10% solid volume and the rest is pore spaces that are filled predominantly with water.
One of the limitations of the aforementioned biolytic filtration protocol is that the surface area of the bed determines the amount of wastewater that can be regularly applied over a long period of time, and the amount of treatment possible is dependent upon the depth and volume of the bed and the hydraulic retention time in the bed. The depth of the bed however cannot be increased beyond a certain limit without the lower layers of the bed being crushed by the weight of the bed itself and the pore spaces destroyed so that blockage can result.
A second limitation is that the surface layer of the bed is by far the most biologically active and diverse zone where the most rapid biolysis takes place. Both living organism population density and species diversity decrease with humus matrix depth. The surface area of the biolytic filter bed container therefore limits the amount of wastewater or high solids slurry that can be applied to the biolytic filter bed, and the failure mode is related to the capacity of air and water to penetrate into the bed.
A third limitation is that the treatment of wastewater by the humus matrix, which requires removal of dissolved and suspended organic material, is compromised when typical flow peaks are applied to the bed as they create channel flow through the bed which erodes the bed so adding suspended solids to the filtrate and results in short effluent retention times.
A fourth limitation of the biolytic filter is that the biological activity in the system is vulnerable to flooding or prolonged inundation. If the adult population of the living organisms in the system are drowned, the population takes several weeks to recover and may need re-inoculating. This could be a logistical problem and considerable expense in a remote installation.